Hi, honey, we need to talk. After fucking a black guy, I came to the realization that you're inadequacy as a man has made me sexually resent you. I had no idea what I've been missing out on - all the right ways I could be fucked. You've been such a disappointment over the years and your sex life ends here.

No, we don't need to break up, but I will be having sex with other men.
With that being said, I'm going to lay out some ground rules on how this marriage is going to work. Pay attention, sweetheart, you're a cuckold now.